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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 263 (1985), S. 778-781 
    ISSN: 1435-1536
    Keywords: Gelatin ; ionic surfactants ; adsorption ; surface rheology ; octadecanoic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Surface rheological measurements of octandecanoic acid monolayers spread on gelatin solutions were performed. The interaction of the spread monolayer with the gelatin involves a strong rise of the solidity of the surface structure with distinct viscoelastic properties and is comparable with the experimental findings looking into the interaction between gelatin and an ionic surfactant. The results found by the addition of sodium-dodecylsulfate to the gelatin solution are discussed, assuming the formation of a multilayer consisting of octadecanoic acid molecules interacting to a negligible degree with the gelatin-surfactant complexes displaced from the surface. The surface rheological parameters are influenced by both layers in opposition to the dynamic behaviour at compression and dilation described in the first part of this paper. An analogous effect is found if the cationic hexadecyltrimethylammoniurn-bromide is added to the gelatin solution. The influence of CTAB is interpreted as the consequence of a steric hindrance, caused by the concentration of groups with opposite charges on the small polar ranges of the gelatin molecules. As a particular interaction of octadecanoic acid with the complexes is possible, a mixed adsorption layer is formed and the high solidity of the surface layer is prevented by the presence of molecules not interacting with the complexes.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 266 (1988), S. 926-929 
    ISSN: 1435-1536
    Keywords: Adsorption ; interfacial tension ; gelatin ; sodium dodecylsulphate ; toluene ; diethylphthalate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The adsorption isotherms between aqueous solutions of sodium dodecylsulphate and gelatin against air, toluene, or diethylphthalate were determined using the spinning drop method. The results qualitatively and quantitatively agreed with those found by surface tension measurements on sodium dodecylsulphate/gelatin solutions using the ring method in the version of Du Noüy. Interaction between gelatin and the surfactant will yield complexes which are more interfacially active than the components by themselves. The saturation of the interfaces occurs at lower concentrations than in solutions of the single components.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-1536
    Keywords: Gelatin ; hexadecyl- and dodecyl-ammonium bromide ; circular dichroism ; gelatin triple helical structure ; influence of temperature ; pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The interaction between cationic surfactants (hexadecyl and dodecyl trimethyl ammonium bromide) and gelatin was characterized by measuring the circular dichroism. The interaction between the cationic surfactants and gelatin is weak in comparison to that of anionic surfactants. When the concentration of cationic surfactants is sufficiently low, refolding of the gelatin-strands to the triple helical structure by rechilling the solution from 298 K to 283 K is complete. The triple helical content of the solution is affected more strongly by the cationic surfactants in acidic solution than at pHs 7 or 10. The interaction depends on the apolar group of the surfactant and is found to be stronger for DTAB than for CTAB at 298 K. Coagulation of the hydrophobic gelatin-cationic surfactant complexes does not comprise that pan of gelatin which is able to refold the triple helical structure. Therefore, the gelatin-strands of lower molecular weights are thought to react favorably with the surfactant ions.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 263 (1985), S. 749-755 
    ISSN: 1435-1536
    Keywords: Gelatin ; surfactant ; octadecanoic acid ; dynamic behaviour ; monolayer ; radio-tracer technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Using the radio-tracer technique the dynamic behaviour of a14C-octadecanoicacid monolayer spread on a gelatin adsorption layer was investigated. The experimental set-up and conditions are given. It was shown that the dynamic behaviour significantly differs form that of a14C-octadecanoic-acid monolayer spread on a 10−2 M/dm3 HCl solution. The differences were explained on the basis of the ionic interactions of the octadecanoic acid monolayer with the gelatin. The aimed blocking of the ionic groups of the gelatin by means of an anionic (SDS) and a cationic (CTAB) surfactant lead to the result that the dynamic behaviour of the spread monolayer did not differ from that spread on a gelatin-free aqueous solution. So the addition of SDS and CTAB to the gelatin solution dependent upon the concentration used, leads to mixed surfactant/gelatin complexes or to the formation of a multilayer system consisting on an octadecanoic monolayer on the top of a gelatin-surfactant complex adsorption layer. The restriction of the interaction between the spread monolayer and the gelatin by both surfactants could be explained as the result of a sterical hindrance.
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  • 5
    ISSN: 1435-1536
    Keywords: Circular dichroism ; gelatin ; sodium alkyl sulphates ; aqueousgelatinsolutions ; secondary structure ; pH ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The modification of the triple helical structure in aqueous gelatin solutions by changing pH and adding alkyl sulphates at 298 K and after rechilling the solution to 283 K was investigated by CD-measurement. At 298 K the triple helical content at the IEP of the gelatin has its maximum value. It is only weakly affected by adding sodium dodecyl sulphate (SDDS) at concentrations 〈10−4 M/dm3. The unfolding of the triple helix affected by pH and SDDS is reversible by rechilling the solution. The triple helical content of gelatin solutions decreases at SDDS concentrations higher than 10−4 M/dm3. In all cases the decrease of the amount of triple helical structure is connected with an increase of the cis-configuration in single chains and leads to chain reversals. At sufficiently high SDDS concentrationsβ-sheets are formed. These changes are thermally irreversible. Sodium decyl sulphate (SDS) has a more minor influence than SDDS except in the range of the c.m.c. of SDS. At sufficiently high SDS concentrations,β-turns appear.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 264 (1986), S. 97-102 
    ISSN: 1435-1536
    Keywords: Gelatin ; surfactant ; foam film ; thickness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of ionic surfactants (sodium-dodecylsulfate and cetyltrimethylammonium-bromide) on the thickness of gelatin foam films was investigated. The thickness of pure gelatin films was found to be 80 to 〈 100 nm. Maximum thicknesses are obtained within the range of the isoelectrical point. Foam films stabilized by gelatin-surfactant complexes are found to form common black films with a thickness of 8 to 12 nm. When the surfactant concentration exceeds the binding capacity of the gelatin the common black films turn into Newton-black films with a thickness comparable to that of a pure surfactant solution.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1435-1536
    Keywords: Circulardichroism ; gelatin ; nonionicsurfactants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Using CD-measurements the influence of nonionic surfactants (dodecyl polyoxyethylene, ethoxylated para tert. octyl phenol, commercial nonionic WON 100 and octyl diethyl phosphinoxid) on the secondary structure of gelatin in aqueous solutions was investigated. At surfactant concentrations smaller than the c.m.c. the triple helical content of the gelatin is increased. At concentrations exceeding the c.m.c. the triple helical content decreases. Chain reversals of the peptide chains after the destruction of the triple helical structure were shown to appear in acidic environment at 298 K. This destruction is reversible by rechilling the solution.
    Type of Medium: Electronic Resource
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